1. Field of the Invention
The present invention relates to a mobile data terminal and more particularly to a mobile data terminal having an infrared communication capability.
2. Description of the Related Art
Mobile data terminals having an infrared communication capability are disclosed in, e.g., Japanese patent laid-open publication No. 4-313182, Japanese utility model laid-open publication No. 5-55683, and Japanese patent laid-open publication No. 9-167997. The data terminals taught in these documents (remote control system in laid-open publication No. 5-55683) each have an infrared communication function in addition to various conventional functions including a character input function, a data storage function, and a telephone directory function. With the infrared communication function, it is possible to interchange various data with another equipment by using infrared rays.
Generally, infrared communication needs a great current for driving a light emitting device. The current for driving the light emitting device is even greater than a current for executing a function other than the infrared communication function.
A mobile data terminal is rarely connected to a commercial power source and usually powered by a miniature battery mounted thereon. Therefore, infrared communication consuming a great current reduces the life of the battery. Moreover, when the remaining capacity of the battery is small, the data terminal practically fails to effect infrared communication.
It is therefore an object of the present invention to provide an improved mobile data terminal having an infrared communication capability.
It is another object of the present invention to provide a mobile data terminal capable of extending the duration of infrared communication available therewith.
It is a further object of the present invention to provide a mobile data terminal capable of controlling a drive current for an infrared light-emitting device in accordance with the remaining capacity of a battery.
In accordance with the present invention, a mobile data terminal having an infrared communication capability includes an infrared communication section for effecting infrared communication with another equipment, a drive controller for controllably driving the infrared communication section, and a starting section for starting the infrared communication. The drive controller controls, in response to a start of the infrared communication, a drive current to be fed to the infrared communication section.
Also, in accordance with the present invention, a mobile data terminal having an infrared communication capability includes an infrared communication section for effecting infrared communication with another equipment, a drive section for driving the infrared communication section, a starting section for starting the infrared communication, and a controller for controlling the drive section in response to a start of the infrared communication. The controller controls, in response to the start of the infrared communication, a distance which infrared rays to issue from the infrared communication section reach.
Further, in accordance with the present invention, a mobile data terminal having an infrared communication capability includes at least two infrared communication sections each for effecting infrared communication with another equipment, a drive section for driving the infrared communication sections, a starting section for starting the infrared communication, and a controller for controlling the drive section in response to a start of the infrared communication. The controller selects, in response to a start of the infrared communication, one of the infrared communication sections and causes it to effect the infrared communication.